Michael D. Cohen, President Trump’s former lawyer and fixer, met last month with federal prosecutors in Manhattan, offering information about possible irregularities within the president’s family business and about a donor to the inaugural committee, according to people familiar with the matter.

Mr. Cohen, who worked at the Trump Organization for a decade, spoke with the prosecutors about insurance claims the company had filed over the years, said the people, who did not elaborate on the nature of the possible irregularities.

While it was not clear whether the prosecutors found Mr. Cohen’s information credible and whether they intended to pursue it, the meeting suggests that they are interested in broader aspects of the Trump Organization, beyond their investigation into the company’s role in the hush money payments made before the 2016 election to women claiming to have had affairs with Mr. Trump. Mr. Cohen pleaded guilty last summer to arranging those payments.

The prosecutors also questioned Mr. Cohen about a donor to the president’s inaugural committee, Imaad Zuberi, a California venture capitalist and political fund-raiser, according to the people familiar with the matter, who were not authorized to discuss the confidential meeting. Around the time that Mr. Zuberi contributed $900,000 to the committee, he also tried to hire Mr. Cohen as a consultant and wrote him a substantial check, one of the people said.

Although Mr. Cohen did not go through with the arrangement, he was building a consulting business at the time with clients who sought to understand and have access to the Trump administration.

A spokesman for Mr. Zuberi, Steve Rabinowitz, confirmed the check on Friday, saying it was for $100,000 and never cashed. Mr. Zuberi, the only person directly referenced in a recent subpoena the prosecutors sent the inaugural committee, had previously denied having any dealings with Mr. Cohen beyond a few conversations.

There was no indication that Mr. Cohen, who is scheduled to begin serving a three-year prison sentence in May, implicated Mr. Trump in the possible irregularities discussed during the meeting last month. If prosecutors concluded that Mr. Cohen’s information was truthful and valuable, they could ask the judge who sentenced him to reduce his prison term.

The White House referred questions to the Trump Organization. A spokeswoman at the company did not respond to requests for comment. In the past, the president has accused Mr. Cohen of lying to try to reduce his sentence.

Lanny Davis, a lawyer and adviser to Mr. Cohen, would not comment on the investigations beyond saying that his client was “interested in cooperating with and assisting” the prosecutors “in any way they believe is helpful.”

A spokesman for the United States attorney’s office in Manhattan, known as the Southern District of New York, declined to comment.

The prosecutors recently sought to interview Trump Organization executives, according to a person briefed on the request, which was previously reported by CNN. The nature of the questions they were seeking to ask was not known.

So far, Mr. Cohen is the only person sentenced to significant prison time in various investigations connected to Mr. Trump.

In August, Mr. Cohen pleaded guilty to breaking campaign finance laws for his role in the hush money payments, as well as tax and bank crimes. In a separate case brought by Robert S. Mueller III, the special counsel, Mr. Cohen pleaded guilty in November to lying to Congress about the timing of negotiations to build a Trump skyscraper in Moscow, and about the extent of Mr. Trump’s involvement in the plans.

In a memo to the court before he was sentenced in December, Mr. Cohen’s lawyers wrote that he was being disproportionately punished for “conduct that is routinely pursued through noncriminal enforcement,” referring to his admission of tax evasion. His lawyers drew a comparison to celebrities who received either fines or far less time after being charged with extensive tax fraud.

The session with the Southern District prosecutors was not the first time Mr. Cohen provided information that could possibly lead to a reduced sentence. Earlier, Mr. Cohen met twice with the prosecutors to assist their investigation of the payments to women, including the Trump Organization’s decision to reimburse Mr. Cohen for $130,000 he paid to the pornographic film actress Stormy Daniels.

In an interview in December, Mr. Cohen told George Stephanopoulos of ABC News that he was “done with the lying.” He went on: “I am done being loyal to President Trump, and my first loyalty belongs to my wife, my daughter, my son and this country.

Federal law allows prosecutors to seek — and a judge to grant — a reduced prison term for a defendant who offers “substantial assistance in investigating or prosecuting another person” within a year of being sentenced. The same rule would also allow the judge to consider assistance Mr. Cohen provided, before his sentencing, to the special counsel. Last year, he met seven times with prosecutors from Mr. Mueller’s office.

The continued scrutiny of the Trump family business and inaugural committee from the Southern District comes as Mr. Mueller is said to be wrapping up his investigation. Once he completes a report with his findings, various aspects of his investigation are expected to live on in the Southern District and other United States attorneys offices.

Mr. Cohen declined to seek a formal cooperation deal with the Southern District, which would have required him to disclose any crimes he had committed or had been aware of, and would have delayed his sentencing. His decision to forgo such an agreement most likely contributed to the severity of his sentence; his lawyer had argued for no prison time.

Mr. Trump had offered a different view, saying late last year that Mr. Cohen should serve a “full and complete” prison sentence. And as Mr. Cohen remained in the spotlight as a likely witness before Congress, Mr. Trump intensified his attacks on his former employee, urging prosecutors and the media to scrutinize Mr. Cohen’s family.

The attacks led Mr. Cohen to postpone a planned appearance before the House oversight committee earlier this month. But this week, the committee announced that the testimony was back on for next Wednesday and that Democrats planned to question Mr. Cohen about “the president’s business practices.”

Mr. Cohen has also agreed to testify behind closed doors before the House and Senate Intelligence Committees.

Mr. Cohen was originally scheduled to begin his prison term next month, but his lawyers cited the congressional testimony — as well as recent shoulder surgery — as a reason for a two-month delay. The judge overseeing Mr. Cohen’s case granted the request on Wednesday.

Benjamin Weiser contributed reporting.

A version of this article appears in print on , on Page A1 of the New York edition with the headline: Cohen Offers New Information On the Trump Family Business . Order Reprints | Today’s Paper | Subscribe